He was an ancient Greek philosopher and scientist born in the city of Stagira, Chalkidice, on the northern periphery of Classical Greece
Alchemy Part 1
300 BC - 500
332 BC Alexander the Great had conquered Egypt
Greek philosophers became interested in the Egyptian religion. Greek views of how matter is made up of the four elements of nature were merged with Egyptian religion.
The result was Khemia, the Greek word for Egypt.
The word Alchemy came from the word Khemia, which means Egypt.
Alchemy covers several philosophical traditions spanning some four millennia and three continents.
The start of Western alchemy may generally be traced to ancient and Hellenistic Egypt, where the city of Alexandria was a center of alchemical knowledge, and retained its pre-eminence through most of the Greek and Roman periods.
Alchemy Part 2
600 - 700
600 A.D. Arabs occupied Egypt and further developed the science, spread it to the West (Spain) in 700s.
Metals are made up of mercury and sulfur in varying proportions.
Gold is the perfect metal and all others were “Baser” metals, capable
of being transmuted into gold by means of a substance known as the
Alchemists applied this concept of purification and search for
perfection to the human condition, and sought spiritual purification and immortality
Alchemy Part 3
1500 - 1590
Eventually, by the 16th Century, the alchemists in Europe had separated into two groups:
In the west, alchemists focused on the discovery of new compounds, reactions, and chemical processes - leading to what is now the science of chemistry.
The second group continued to look at the more spiritual, metaphysical side of alchemy, continuing the search for immortality and the transmutation of base metals into gold. This led to the modern day idea of alchemy.
1600 - 1700
Living organisms are fundamentally different from non-living entities because they contain a “vital spirit”.
Living things are thus governed by different principles than are inanimate things.
The notion that bodily functions are due to a vitalistic principle existing in all living creatures has roots going back at least to ancient Egypt.
Biologists now consider vitalism to have been refuted by empirical evidence, and hence as belonging to the realm of religion rather than that of science.
The Phlogiston Theory
1667 - 1700
from the Ancient Greek phlogistón "burning up"
first stated in 1667 by Johann Joachim Becher
postulated the existence of a fire-like element called "phlogiston",
which was contained within combustible bodies and released
A substance that burned did so because it contained Phlogiston.
Carbon Dioxide, no longer capable of burning was called
Anton La Voisier
1743 - 1794
Father of Modern Chemistry because he relied on quantitative observation to develop conclusions.
Dispelled the Phlogiston Theory by proving that Oxygen causes combustion.
Discovered the Law of Conservation of Mass: By proving that the mass of a metal oxide = the mass of the metal plus oxygen when the metal oxide decomposes.
Matter can change form, but cannot be created nor destroyed in a chemical reaction.
Beheaded during French Revolution
Discovered that electrical charges come in 2 varieties – positive and negative. Like charges repel, opposite charges attract.
Joseph Louis Proust
The Law of Definite Proportions, sometimes called The Law of Constant Composition, states that a chemical compound always contains exactly the same proportion of elements by mass.
John Dalton: Father of Atomic Theory
1766 - 1844
A. Matter is made up of atoms that are indivisible and indestructible.
B. All atoms of an element are identical. (Known now to be untrue!)
C. Atoms of different elements have different weights and different chemical properties.
D. Atoms of different elements combine in simple whole numbers to form compounds.
E. Atoms cannot be created or destroyed. When a compound decomposes, the atoms are recovered unchanged.
William Crookes et. al.
1861 - 1880
A. Cathode Ray Tube (CRT)
CRT – a glass tube that is evacuated (contains no air or matter) coated with fluorescent paint. When connected to a battery, the paint glows, indicating that there is some type of radiation streaming from the battery (the cathode)
B. Paddle wheel placed in CRT:
When Crookes placed a paddle wheel in the CRT and turned on the battery, the wheel spun. Since the tube was evacuated, this told Crookes that the Cathode Ray has mass.
Sir John Joseph Thomson
A. Continued experimenting on the CRT:
JJ Thomson used charged plates to deflect the cathode ray. Found the ray deflected away from the negative plate, and toward the positive.
B. Deduced that the cathode ray was made of:
Negative particles. He named them electrons.
Ernest Rutherford Part 1
1900 - 1905
A. @ 1900: Classification of radiation
B. @ 1910: Famous Gold Foil Experiment
1. What he did:
- Stretched a sheet of gold foil in a tin can and coated the inside of the can with fluorescent paint.
- Aimed a ray of alpha radiation (+ charges) at the foil.
- Expected that the alpha rays would pass right through the metal atoms in the foil, and the
fluorescent coating would light up right behind the foil.
2. What he observed:
- 99.9% of the time, the ray lit up the can right behind the foil.
- .1% of the time, the ray lit up the can OPPOSITE the foil. (behind the alpha source)
- This told him that the ray had hit something massive and dense in the center of the atom.
3. What he deduced:
A. Atoms are mostly empty space.
B. There must be a solid core in the center of the atom.
C. The core must be positively charged, since it deflected an alpha ray
Discovered radioactivity in Uranium ore.
Curies (Marie and Pierre)
Discovered and isolated polonium and radium from uranium ores.
Ernest Rutherford - Part 2
1905 - 1910
Calculated the mass and charge of an electron
Robert Andrews Millikan was an American experimental physicist honored with the Nobel Prize for Physics in 1923
Discovered the neutron
Won Nobel Prize in 1935
In 1941, he wrote the final draft of the MAUD Report, which inspired the U.S. government to begin serious atomic bomb research efforts.
He was the head of the British team that worked on the Manhattan Project during the Second World War.
He was knighted in England in 1945 for his achievements in physics.